Modern complex safety-critical socio-technical systems (STSs) operate in an environment that requires high levels of human-machine interaction. Given the potential for catastrophic events , understanding human errors is a critical research area spanning disciplines such as management science, cognitive engineering, resilience engineering, and systems theory. However, a research gap remains when researching how errors impact system performance from a systemic perspective. This dissertation employs a systematic methodology and develops models that explore the relationship between errors and system performance, considering both macro-organizational and micro-worker perspectives. In Essay 1, the focus is on how firms respond to serious errors (catastrophic events), by exploring the oscillation behavior associated with the organizational learning and forgetting theory. The proposed simulation model contributes to the organizational science literature with a comprehensive approach that assesses the firm's response time to "serious" errors when the firm has a focus on safety with established safety thresholds. All of these considerations have subsequent impact on future performance. Essay 2 explores the relationship between safety-critical system's workers' workload, human error, and automation reliance for the Belgian railway traffic control center. Key findings include a positive relationship between traffic controller performance and workload, and an inverted U-shaped relationship with automation usage. This research offers new insights into the effects of cognitive workload and automation reliance in safety-critical STSs. Essay 3 introduces a calibrated System Dynamics model, informed by empirical data and existing theories on workload suboptimality. This essay contributes to the managerial understanding of workload management, particularly the feedback mechanism between operators' workload and human errors, which is driven by overload and underload thresholds. The model serves as a practical tool for managerial practitioners to estimate the likelihood of human errors based on workload distributions. Overall, this dissertation presents an interdisciplinary and pragmatic approach, blending theoretical and empirical methodologies. Its broad impacts extend across management science, cognitive engineering, and resilience engineering, contributing significantly to the understanding and management of safety-critical socio-technical systems. / Doctor of Philosophy / This dissertation is motivated by the increasing autonomy in infrastructure systems designed to enhance safety performance. Yet paradoxically, we continue to witness system failures leading to catastrophic disasters. High-profile incidents such as the Metro-North train derailment in New York City, the Boeing 737 MAX plane crashes, and the Challenger and Columbia space shuttle accidents highlight this contradiction. This research delves into safety-critical systems where the intricate collaboration between humans and machines is crucial, and where even minor human errors can lead to disastrous consequences. This dissertation is presented in three parts. In the first part I examine how firms react to serious errors. The study focuses on their learning processes following safety incidents and the potential for these lessons to be forgotten over time. I introduced a simulation model grounded in the organizational science literature, offering deeper insights into how companies respond to errors, including changes in safety focus, safety culture, and policy, and the impact of these factors on future company's performance. The second part shifts to a worker-centered perspective, exploring the relationship between workload, performance, and automation usage among traffic controllers. The findings indicate that while performance can improve with an increase in workload up to a certain threshold, excessive reliance on automation may lead to a decline in performance. This part of the study sheds light on how cognitive workload and technology usage influence operators in safety-critical roles. The final part of the dissertation presents another simulation model, this time focusing on how workload, and the resulting stress and boredom due to workload, influence the likelihood of errors. Utilizing real operational data from the Belgian railway transportation system, this model aids managers in understanding how to optimally balance workloads to minimize error risks. Overall, this dissertation takes an interdisciplinary and pragmatic approach, merging theoretical concepts with empirical data. Its extensive impact spans management science, cognitive engineering, and resilience engineering, significantly enhancing our comprehension and management of safety-critical socio-technical systems.

Las nuevas aplicaciones y servicios web, cada vez má¡s populares en nuestro día a día, han cambiado completamente la forma en la que los usuarios interactúan con la Web. En menos de media década, el papel que juegan los usuarios ha evolucionado de meros consumidores pasivos de información a activos colaboradores en la creación de contenidos dinámicos, típicos de la Web actual. Y, además, esta tendencia se espera que aumente y se consolide con el paso del tiempo. Este comportamiento dinámico de los usuarios es una de las principales claves en la definición de cargas de trabajo adecuadas para estimar con precisión el rendimiento de los sistemas web. No obstante, la dificultad intrínseca a la caracterización del dinamismo del usuario y su aplicación en un modelo de carga, propicia que muchos trabajos de investigación sigan todavía empleando cargas no representativas de las navegaciones web actuales. Esta tesis doctoral se centra en la caracterización y reproducción, para estudios de evaluación de prestaciones, de un tipo de carga web más realista, capaz de imitar el comportamiento de los usuarios de la Web actual. El estado del arte en el modelado y generación de cargas para los estudios de prestaciones de la Web presenta varias carencias en relación a modelos y aplicaciones software que representen los diferentes niveles de dinamismo del usuario. Este hecho nos motiva a proponer un modelo más preciso y a desarrollar un nuevo generador de carga basado en este nuevo modelo. Ambas propuestas han sido validadas en relación a una aproximación tradicional de generación de carga web. Con este fin, se ha desarrollado un nuevo entorno de experimentación con la capacidad de reproducir cargas web tradicionales y dinámicas, mediante la integración del generador propuesto con un benchmark de uso común. En esta tesis doctoral también se analiza y evalúa por primera vez, según nuestro saber y entender, el impacto que tiene el empleo de cargas de trabajo dinámicas en las métrica / Peña Ortiz, R. (2013). Accurate workload design for web performance evaluation [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/21054

The continuous shrink of transistor sizes has allowed more complex and powerful devices to be implemented in the same area, which provides new capabilities and functionalities. However, this complexity increase comes with a considerable rise in power consumption. This situation is critical in portable devices where the energy budget is limited and, hence, battery lifetime defines the usefulness of the system. Therefore, power consumption has become a major concern in the design of real-time multicore embedded systems. This dissertation proposes several techniques aimed to save energy without sacrifying real-time schedulability in this type of systems. The proposed techniques deal with different main components of the system. In particular, the techniques affect the task partitioner and the scheduler, as well as the memory controller. Some of the techniques are especially tailored for multicores with shared Dynamic Voltage and Frequency Scaling (DVFS) domains. Workload balancing among cores in a given domain has a strong impact on power consumption, since all the cores sharing a DVFS domain must run at the speed required by the most loaded core. In this thesis, a novel workload partitioning algorithm is proposed, namely Loadbounded Resource Balancing (LRB). The proposal allocates tasks to cores to balance a given resource (processor or memory) consumption among cores, improving real-time schedulability by increasing overlapping between processor and memory. However, distributing tasks in this way regardless the individual core utilizations could lead to unfair load distributions. That is, one of the cores could become much loaded than the others. To avoid this scenario, when a given utilization threshold is exceeded, tasks are assigned to the least loaded core. Unfortunately, workload partitioning alone is sometimes not able to achieve a good workload balance among cores. Therefore, this work also explores novel task migration approaches. Two task migration heuristics are proposed. The first heuristic, referred to as Single Option Migration (SOM ), attempts to perform only one migration when the workload changes to improve utilization balance. Three variants of the SOM algorithm have been devised, depending on the point of time the migration attempt is performed: when a task arrives to the system (SOMin), when a task leaves the system (SOMout), and in both cases (SOMin−out). The second heuristic, referred to as Multiple Option Migration (MOM ) explores an additional alternative workload partitioning before performing the migration attempt. Regarding the memory controller, memory controller scheduling policies are devised. Conventional policies used in Non Real-Time (NRT) systems are not appropriate for systems providing support for both Hard Real-Time (HRT) and Soft Real-Time (SRT) tasks. Those policies can introduce variability in the latencies of the memory requests and, hence, cause an HRT deadline miss that could lead to a critical failure of the real-time system. To deal with this drawback, a simple policy, referred to as HR- first, which prioritizes requests of HRT tasks, is proposed. In addition, a more advanced approach, namely ATR-first, is presented. ATR-first prioritizes only those requests of HRT tasks that are necessary to ensure real-time schedulability, improving the Quality of Service (QoS) of SRT tasks. Finally, this thesis also tackles dynamic execution time estimation. The accuracy of this estimation is important to avoid deadline misses of HRT tasks but also to increase QoS in SRT systems. Besides, it can also help to improve the schedulability of the systems and reduce power consumption. The Processor-Memory (Proc-Mem) model, that dynamically predicts the execution time of real-time application for each frequency level, is proposed. This model measures at the first hyperperiod, making use of Performance Monitoring Counters (PMCs) at run-time, the portion of time that each core is performing computation (CPU ), waiting for memory (MEM ), or both (OVERLAP). This information will be used to estimate the execution time at any other working frequency / March Cabrelles, JL. (2014). Dynamic Power-Aware Techniques for Real-Time Multicore Embedded Systems [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48464

Multi-criteria scheduling provides the opportunity to create mathematical optimization models that are applicable to a diverse set of problem domains in the business world. This research addresses two different employee scheduling applications using multi-criteria objectives that present decision makers with trade-offs between global optimality and the level of disruption to current operating resources. Additionally, it investigates a scheduling problem from the product testing domain and proposes a heuristic solution technique for the problem that is shown to produce very high-quality solutions in short amounts of time. Chapter 2 addresses a grant administration workload-to-staff assignment problem that occurs in the Office of Research and Sponsored Programs at land-grant universities. We identify the optimal workload assignment plan which differs considerably due to multiple reassignments from the current state. To achieve the optimal workload reassignment plan we demonstrate a technique to identify the n best reassignments from the current state that provides the greatest progress toward the utopian solution. Solving this problem over several values of n and plotting the results allows the decision maker to visualize the reassignments and the progress achieved toward the utopian balanced workload solution. Chapter 3 identifies a weekly schedule that seeks the most cost-effective set of coach-to-program assignments in a gymnastics facility. We identify the optimal assignment plan using an integer linear programming model. The optimal assignment plan differs greatly from the status quo; therefore, we utilize a similar approach from Chapter 2 and use a multiple objective optimization technique to identify the n best staff reassignments. Again, the decision maker can visualize the trade-off between the number of reassignments and the resulting progress toward the utopian staffing cost solution and make an informed decision about the best number of reassignments. Chapter 4 focuses on product test scheduling in the presence of in-process and at-completion inspection constraints. Such testing arises in the context of the manufacture of products that must perform reliably in extreme environmental conditions. Each product receives a certification at the successful completion of a predetermined series of tests. Operational efficiency is enhanced by determining the optimal order and start times of tests so as to minimize the make span while ensuring that technicians are available when needed to complete in-process and at-completion inspections We first formulate a mixed-integer programming model (MILP) to identify the optimal solution to this problem using IBM ILOG CPLEX Interactive Optimizer 12.7. We also present a genetic algorithm (GA) solution that is implemented and solved in Microsoft Excel. Computational results are presented demonstrating the relative merits of the MILP and GA solution approaches across a number of scenarios. / Ph. D. / Multi-criteria scheduling provides the opportunity to create mathematical optimization models that are applicable to a diverse set of problem domains in the business world. This research addresses two different employee scheduling applications using multi-criteria objectives that present decision makers with trade-offs between global optimality and the level of disruption to current operating resources. Additionally, it investigates a scheduling problem from the product testing domain and proposes a heuristic solution technique for the problem that is shown to produce very high-quality solutions in short amounts of time. Chapter 2 addresses a grant administration workload-to-staff assignment problem that occurs in the Office of Research and Sponsored Programs at land-grant universities. Solving this problem and plotting the results allows the decision maker to visualize the number of reassignments and the progress achieved toward the utopian balanced workload solution. Chapter 3 identifies a weekly schedule that seeks the most cost-effective set of coach-to-program assignments in a gymnastics facility. Again, the decision maker can visualize the trade-off between the number of reassignments and the resulting progress toward the utopian staffing cost solution and make an informed decision about the best number of reassignments. Chapter 4 focuses on product test scheduling in the presence of in-process and at-completion inspection constraints. Such testing arises in the context of the manufacture of products that must perform reliably in extreme environmental conditions. Each product receives a certification at the successful completion of a predetermined series of tests. Computational results are presented demonstrating the relative merits of the mixed integer linear programming model and the genetic algorithm solution approaches across a number of scenarios.

Given the continuing deployment of total quality control and total quality management initiatives by organizations, employees have seen changes in their work environment. Furthermore, the impact of downsizing has resulted in operators becoming responsible for the quality of their own processes. This study tested the impact of various display alternatives of control chart data on decision performance and mental workload.  The control charts were shown as multiple two dimensional displays, a composite two dimensional display, and a composite three dimensional perspective display. Multiple two dimensional displays were found to have significantly higher decision accuracy and decision confidence ratings than either composite displays. No significant difference in decision accuracy and decision confidence ratings was found among the composite displays. The type of display did not have a significant effect on decision time. Mental workload was also found to be significantly affected by the type of display used. Multiple two dimensional displays imposed significantly lower levels of mental workload than either composite display. No significant difference in mental workload was found among the composite displays. These results indicated that multiple two dimensional displays should be used when control chart data from multiple processes must be displayed. / Master of Science

Denna studie undersökte huruvida artificiell intelligens relaterar till stress och arbetsbelastning bland kontorsarbetare. Genom datan från en enkätstudie med 91 deltagare genomfördes två regressionsanalyser och en korrelationsanalys. Resultaten visade att det fanns en statistiskt signifikant korrelation mellan användningen av artificiell intelligens och både stress och arbetsbelastning. Enkäten var uppbyggd av två mätverktyg (PSS) perceived stress scale och (QWI) quantitative workload inventory. Resultaten visar att AI användning associeras med ökad arbetsbelastning, samt minskad stress bland kontorsarbetare. Denna forskning pekar på behovet av att noggrant överväga de psykosociala effekterna av AI-implementering på arbetsplatsen, behovet av att vidta åtgärder för att hantera eventuella negativa konsekvenser för personalens välbefinnande och produktivitet, samt framföra de positiva aspekter som AI skulle kunna bidra till. Utöver detta hade det varit intressant att utföra en kvalitativ studie för att ta reda på bakgrunden till korrelationen och resultatet som framgick i regressionsanalysen. / This study examined whether artificial intelligence relates to stress and workload among office workers. Using data from a survey study with 91 participants, two regression analyses and a correlation analysis were conducted. The results showed that there was a statistically significant correlation between the use of artificial intelligence and both stress as well as workload. The survey was constructed by using two measurement tools: The Perceived Stress Scale (PSS) and The Quantitative Workload Inventory (QWI). The results indicate that AI usage is associated with increased workload, as well as decreased stress among office workers. This research highlights the need to carefully consider the psychosocial effects of AI implementation in the workplace, to take measures and manage any potential negative consequences for employee well-being and productivity, while also emphasizing the positive aspects that AI could contribute. Additionally, it would be interesting to conduct a qualitative study to investigate the background of the correlation and the results presented in the regression analysis.

No description available.

Lärare har en viktig funktion för samhället när det kommer till att undervisa elever och hjälpa dem att få kunskaper som de kan använda i sina liv. Förutom förväntningar som handlar om undervisning kan läraryrket även inkludera en social aspekt där lärare stöttar och hjälper elevergenom deras skolgång. Detta arbete kan vara känslomässigt utmanade för lärare och arbetsbelastningen kan påverkas av att arbetsuppgifter som sträcker sig utanför undervisning genomförs. Denna kvalitativa studie om lärares upplevelser om utmaningar och om emotionellt arbete baseras på sju semi-strukturerade intervjuer med lärare. Data som samlats in från intervjuerna har analyserats genom teorier och begrepp som handlat om emotionellt arbete, sociala interaktioner och emotionell energi. Resultatet visar att arbete med elever såg många av lärarna som motiverande och meningsfullt jämfört med administrativa arbetsuppgifter som dokumentation, planering och möten. Arbetet kunde vara emotionellt krävande och lärarna upplevde att de dels var tvungna att hantera sina egna känslor, dels välja vilka känslouttryck de visade mot elever. Utmaningar fanns i läraryrket då arbetsdagar kunde bestå av planerade lektioner men även att konflikter, stöd till kollegor och samtal kunde uppstå under arbetsdagen som lärarna upplevde inte alltid handlade om undervisning. Lärarna ansåg att det fanns ett behov att kunna lämna arbetsrelaterade problem på arbetet för att kunna återhämta sig när de lämnat arbetet. / Teachers have an important function for society when it comes to teaching and providing students with knowledge that the students can use in their lives. In addition to expectations related to teaching, the teaching profession can also include a social aspect where teachers support and help student through schooling. This work can be emotionally challenging for teachers and the workload can be affected by tasks that extend beyond teaching. This qualitative study on teacher’s experiences and challenges regarding emotional labor is based on seven semi-structured interviews with teachers. The data collected from the interviews has been analyzed through theories dealing with emotional labor, social interaction, and emotional energy. The results show that many of the teachers believed that working with student was motivating and meaningful compared to administrative task such as documentation, planning and meetings. The work could be emotionally demanding, and the teachers felt that they partly had to manage their own emotions and to manage what emotions they showed toward students. Challenges existed as the workdays could consist of planned lessons, conflicts, conversations with students and supporting coworkers. The teachers considered the activities besides the planned lessons to sometimes put them in a position that wasn’t about teaching. The teachers felt that there was a need to be able to leave work-related problem at work to recover when they left work.

No / NHS maternity services in England must increase productivity if the NHS is to make efficiency savings by 2014. At the same time, it is expected to maintain or improve patient outcomes such as safety and quality. Given staff costs are 60% of the budget; it is likely that either the number or composition of the workforce will need to be changed to meet these targets. In this article, the authors argue that very little is known about the impact of altering the skill mix on either productivity or patient outcomes. Furthermore, it is unclear whether output and outcomes are themselves trade-offs between increased workload, increased number of deliveries and the increased complexity of demand.

京都大学 / 新制・課程博士 / 博士(情報学) / 甲第25511号 / 情博第884号 / 新制||情||148(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 大木 英司, 教授 原田 博司, 教授 山下 信雄 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM